1. Field of the Invention
The present invention relates to a reel for vehicle safety belt and more particularly to a reel for vehicle safety belt of the type in which a rotatable element is adapted automatically to wind the seat belt when it is not in use, the reel also being provided with means to prevent rapid extraction of the belt, especially under accident conditions.
2. Discussion of the Prior Art
Modern safety belts in vehicles, particularly motor cars, are provided with a spring loaded reel comprising a winding spindle, which is arranged in a housing, onto which part of the safety belt is automatically wound when the safety belt is loose. Such safety belts are normally provided with a device for locking the winding spindle so that the safety belt cannot be extracted if the vehicle is suddenly accelerated or decelerated, or if the vehicle turns sharply. Normally the locking device is also such that the safety belt cannot be extracted rapidly, even if the motor car is at rest or moving relatively smoothly or slowly.
It will be appreciated that the prior-proposed safety belt reels have been designed so that a passenger wearing the safety belt can move forwardly relatively easily when not under accident conditions, but are such that the person wearing the safety belt is firmly retained in position when an accident occurs.
It will be appreciated that the spindle of the above-described prior proposed type of retractor reel is normally in an unlocked condition, and is only placed in a locked condition when accident conditions or potential accident conditions are detected either due to a rapid acceleration or deceleration of the vehicle, or due to the safety belt being withdrawn at a relatively high speed.
Many of the prior proposed seat belts have incorporated a control wheel having a toothed periphery. A sensor is provided adapted to sense the acceleration or deceleration of the vehicle in excess of a predetermined limit. When such an acceleration or deceleration is sensed a locking pin or the like is brought into engagement with the toothed periphery of the wheel thus preventing rotation of the wheel. When the seat belt is then paid out the wheel is prevented from rotating, which actuates a locking mechanism to prevent any further length of the seat belt from being paid out.
Such a mechanism also frequently has a "inertia" device so that,if the seat belt is withdrawn rapidly from the reel, again the locking arrangement is actuated to prevent any further length of seat belt being paid out.
One disadvantage with the prior art arrangement is that if the toothed wheel is rotating when an accident occurs, whilst the sensor may sense an acceleration or deceleration in excess of the predetermined limit, it may not be possible to inset the locking pin satisfactorily into the toothed periphery of the wheel to cause the wheel to stop rotating.